The rollover action enables you to automatically roll over to a new index based
on the index size, document count, or age. When a rollover is triggered, a new
index is created, the write alias is updated to point to the new index, and all
subsequent updates are written to the new index.

Rolling over to a new index based on size, document count, or age is preferable
to time-based rollovers. Rolling over at an arbitrary time often results in
many small indices, which can have a negative impact on performance and
resource usage.

You control when the rollover action is triggered by specifying one or more
rollover parameters. The rollover is performed once any of the criteria are
met. Because the criteria are checked periodically, the index might grow
slightly beyond the specified threshold. To control how often the criteria are
checked, specify the indices.lifecycle.poll_interval cluster setting.

New indices created via rollover will not automatically inherit the
policy used by the old index, and will not use any policy by default. Therefore,
it is highly recommended to apply the policy via
index template, including a Rollover alias
setting, for your indices which specifies the policy you wish to use for each
new index.

The rollover action takes the following parameters:

Table 71. rollover Action Parameters

Name

Description

max_size

The maximum estimated size the primary shard of the index is allowed
to grow to. Defaults to null. Optional.

max_docs

The maximum number of document the index should
contain. Defaults to null. Optional.

max_age

The maximum age of the index. Defaults to null. Optional.

These parameters are used to determine when the index is considered "full" and
a rollover should be performed. Where multiple criteria are defined the
rollover operation will be performed once any of the criteria are met.

The following request defines a policy with a rollover action that triggers
when the index size reaches 25GB. The old index is subsequently deleted after
30 days.

Once an index rolls over, index lifecycle management uses the timestamp of the rollover
operation rather than the index creation time to evaluate when to move the
index to the next phase. For indices that have rolled over, the min_age
criteria specified for a phase is relative to the rollover time for indices. In
this example, that means the index will be deleted 30 days after rollover, not
30 days from when the index was created.

To use an index lifecycle management policy, you need to specify it in the index template used to
create the indices. For example, the following template associates my_policy
with indices created from the template my_template.

Creates the index called test-000001. The rollover action increments the
suffix number for each subsequent index.

Designates this index as the write index for this alias.

When the rollover is performed, the newly-created index is set as the write
index for the rolled over alias. Documents sent to the alias are indexed into
the new index, enabling indexing to continue uninterrupted.